Soybean (ie., Glycine max L. Merr.) seeds are recognized to represent one of the most important oilseed crops presently being grown in world. Such seeds provide an excellent source of vegetable oil as well as a source of protein that can serve as an alternative to animal meat products. For instance, tofu and soymilk derived from soybean seeds provide a major source of protein for the people of China and Southeast Asia.
Soybean oil obtained from soybean seeds commonly is utilized in the production of plastic fats suitable for human consumption (e.g., as margarines and shortenings). Such plastic fats frequently comprise a matrix of solid fats wherein interstices present therein are filled with liquid oil. It is recognized that solid fats can crystallize in several forms having different melting points and differing physical properties. These forms commonly are designated .alpha., .beta.', and .beta., with the .beta.' crystalline form having the highest melting point and highest stability. Other forms additionally can be present. The .beta.' crystalline form generally has properties that most commonly are sought in a plastic fat. When the solid portion of the plastic fat contains approximately 15 percent by weight or more of palmitic acid (C16:0) and the remainder is stearic acid (C18:0), it commonly will assume the most advantageous .beta.' crystalline form. However, if the ratio of stearic acid to palmitic acid is higher, then the fat may more readily convert to the less advantageous .beta. form having less desirable physical characteristics.
It generally is recognized that endogenously formed soybean oil commonly will contain a palmitic acid concentration on the order of 12 percent or less by weight based upon the total fatty acid content following the simple crushing and extraction of soybean seeds and the use of a standard analysis technique. It will be recognized by those skilled in the relevant area of technology that the fatty acids commonly are primarily present while esterified with glycerol in the vegetable oil. For instance, palmitic acid is provided as palmitate and stearic acid as a stearate. Following the subsequent hydrogenation of unsaturated fatty acids inherently present therein such oil commonly will still crystallize to form the less desirable .beta. crystalline form. To prevent this in accordance with prior technology, another oil that is richer in palmitic acid, such as cottonseed oil or palm oil, sometimes is blended with the soybean oil. However, such blending nevertheless has posed difficulties. For instance, some consumers consider palm oil to be undesirable from a health standpoint. Also, cottonseed oil tends to be available in considerably more limited quantities than soybean oil and tends to demand a considerably higher cost than the soybean oil component.
It accordingly has been recognized to be desirable to provide improved plants that endogenously form soybean seeds that include a greater concentration of palmitic acid within the oil present therein on a reliable and readily reproducible basis under conventional field growing conditions while under genetic control.
Palmitic acid levels in soybean seed oil in the past frequently have ranged from 9.3 to 17.4 percent by weight based upon the total fatty acid content as reported by E. A. Erickson et al. in "Inheritance of Altered Palmitic Acid Percentage in Two Soybean Mutants" appearing in the Journal of Heredity, Vol. 79, Pages 465 to 468 (1988). Certain mutant soybeans designated C1726 and C1727 were developed through the chemical mutagenesis of the `Century` variety. It was found that C1726 possessed the fap1fap1 allele or gene pair that expressed a lesser concentration of palmitic acid in the oil that averaged 8.6 percent by weight based on the total fatty acid content. Also, C1727 possessed the fap2fap2 allele or gene pair which expressed a greater concentration of palmitic acid in the oil that averaged 17.3 percent by weight based on the total fatty acid content. The palmitic acid content in the oil of the `Century` parent prior to mutagenesis was reported to be 11.5 percent by weight based on the total fatty acid content.
A soybean mutant initially designated A1937NMU-173 possessing the fapxfapx allele or gene pair was described by W. R. Fehr et al. in "Inheritance of Reduced Palmitic Acid Content in Seed Oil of Soybean" appearing in Crop Sci., Vol. 31, Pages 88 to 89 (1991). The A1937NMU-173 line subsequently was redesignated as A22 and the fapxfapx gene pair was redesignated as fap3fap3. A mean palmitic acid content in the oil thereof averaged 6.5 percent by weight based on the total fatty acid content.
Mutant soybeans designated A1937NMU-85 possessing the fap2-bfap2-b allele or gene pair and ElginEMS-421 possessing the fap?fap? allele or gene pair were described by W. R. Fehr et al. in "Inheritance of Elevated Palmitic Acid Content in Soybean Seed Oil" appearing in Crop Sci., Vol. 31, Pages 1522 to 1524 (1991). The A1937NMU-85 line, subsequently designated A21, exhibited an elevated pahnitic acid content of 19.8 percent by weight based on the total fatty acid content. The ElginEMS-421 line subsequently was designated A24 and exhibited an elevated palmitic acid content of 17.9 percent by weight based on the total fatty acid content, and the fap?fap? allele or gene pair present therein subsequently was redesignated fap4fap4. Research there reported indicates that the fap2fap2 allele or gene pair and the fap2-bfap2-b allele or gene pair are present at the same locus or are tightly linked. When the fap2-bfap2-b allele or gene pair and the fap4fap4 allele or gene pair are combined in a single plant, a palmitic acid concentration of greater than 25 percent by weight based on the total fatty acid content was reported in the resulting vegetable oil. This line possessing in combination the fap2-bfap2-b allele or gene pair and the fap4fap4 allele or gene pair initially was designated AX4663-5-4-5 and subsequently was redesignated as A19 and is described in commonly assigned U.S. patent application Ser. Nos. 08/375,340, filed Jan. 19, 1995 (now U.S. Pat. No. 5,557,037), entitled "Soybeans Having Elevated Contents of Saturated Fatty Acids," and 08/376,466, filed Jan. 20, 1995 (now U.S. Pat. No. 5,602,311), entitled "Soybeans and Soybean Products Having High Palmitic Acid Content."
A further discussion of a modified production of palmitic acid in soybean seeds while under genetic control is described by Schnebly et al. in "Inheritance of Reduced and Elevated Palmitate in Mutant Lines of Soybean" appearing in Crop Sci., Vol. 34, Pages 829 to 833 (1994). See also, "Inheritance of Palmitic and Stearic Acid Mutants of Soybean", by D. M. Bubeck et al. appearing in Crop Sci., Vol. 29, Pages 652 to 656 (1989).
It is an object of the present invention to provide under conventional field growing conditions soybean seeds possessing while under genetic control an enhanced level of palmitic acid in the endogenously produced vegetable oil wherein said genetic control is attributable to a new allele.
It is an object of the present invention to provide soybean plants capable upon self-pollination of forming seeds that possess while under genetic control an enhanced level of palmitic acid in the endogenously produced vegetable oil wherein said genetic control is attributable to a new allele.
It is an object of the present invention to provide a vegetable oil derived from soybeans following crushing and extraction that exhibits while under genetic control (as described) an elevated concentration of palmitic acid wherein the level of palmitic acid exceeds that previously available in an endogenously formed soybean seed oil.
It is another object of the present invention to provide in soybeans a novel heretofore unknown homogeneous recessive fap5fap5 gene pair that is capable of elevating palmitic acid production in the endogenously produced vegetable oil present in the seeds thereof.
It is another object of the present invention to combine the homogeneous recessive gene pairs (1) fap2fap2 or fap2-bfap2-b, (2) fap4fap4, and (3) fap5fap5 in a single soybean plant which in combination have been found to make possible the expression while under genetic control of a greater concentration of pahnitic acid in the endogenously formed vegetable oil formed in the soybean seeds of such plant than has heretofore been reported.
It is a further object of the present invention to provide a vegetable oil derived from soybean seeds that contains an elevated endogenously produced saturated fatty acid content while under genetic control which is particularly suited for margarine or shortening production in the absence of hydrogenation.
These and other objects, as well as the scope, nature, and utilization of the claimed invention will be apparent to those skilled in the art from the following detailed description and appended claims.